What do baked goods and the planet Mercury have in common? They both shrink as they cool.
Mercury formed around 4.5 billion years ago and has been slowly contracting ever since. As it loses heat, the planet actually develops cracks similar to those you might see on a cookie or cheesecake right out of the oven. These cracks are known as thrust faults, and they are a sign of Mercury’s ongoing shrinkage.
Researchers study these faults to understand how much Mercury has shrunk over time. Previous estimates suggested a wide range, with shrinkage varying between 1 to 7 kilometers. But a recent study by Loveless and Klimczak developed a new way to measure this shrinkage more accurately.
Their method focuses on the largest faults. Instead of relying on the number of faults in the dataset—which can lead to different shrinkage estimates—the new approach measures the impact of the biggest fault and then scales it. This led to consistent estimates of about 2 to 3.5 kilometers of shrinkage across multiple datasets.
Combining these findings with earlier estimates of additional shrinkage, the total loss in radius is now thought to be between 2.7 and 5.6 kilometers. This important insight helps scientists refine our understanding of Mercury’s long-term thermal history.
The same technique could also apply to other planets with faults, like Mars. This kind of research enhances our grasp of planetary processes and can impact how we study geology beyond Earth.
For more details, you can check out the research published in AGU Advances here.
